<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="utf-8">
    <meta name="viewport"
          content="width=device-width, user-scalable=no, initial-scale=1.0, maximum-scale=1.0, minimum-scale=1.0"/>
    <title>百度搜索框</title>
    <link href="css/bootstrap.css" rel="stylesheet">
    <style>

    </style>
</head>
<body>
<div class="container" style="margin: 40px">
    <div class="input-group">
        <input type="text" class="form-control" placeholder="请输入要搜索的内容">
        <span class="input-group-btn">  <!-- 容易出错点：写成input-group-addon-->
            <button class="btn btn-primary" type="button">百度一下</button>
        </span>
    </div>
</div>


</body>
</html>